Change caching behavior for file:/// paths.

[vzickner]

Ruby changed in on of the recent versions its behavior of URI for files. They introduced URI::File which also allows hostnames for files. This result in a different behavior for the to string method, because it returns with file:///. To avoid this behavior and since there are no credentials for file:, it can be returned directly. See also for reference the new URI::File: https://github.com/ruby/ruby/commit/04883f12c8944922117482d4d446502e5d5d3413

[cfdreddbot]

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[cf-gitbot]

We have created an issue in Pivotal Tracker to manage this:

https://www.pivotaltracker.com/story/show/158546846

The labels on this github issue will be updated when the story is started.

[sclevine]

Thanks for the PR! FYI, this repo is deprecated in favor of libbuildpack: https://github.com/cloudfoundry/libbuildpack/tree/master/packager/buildpack-packager

[vzickner]

Hi @sclevine, I also figured this out. But unfortunately, this repository is still used by for example the https://github.com/cloudfoundry/php-buildpack

[vzickner]

I will reopen this pull request because of the CLA Agreement.